Insulators are such materials in which the conduction cannot take place, due to the large forbidden gap. Examples: Wood, Rubber. The structure of energy bands in Insulators is as shown in the following figure.

Characteristics

The following are the characteristics of Insulators.

·        The Forbidden energy gap is very large.

·        Valance band electrons are bound tightly to atoms.

·        The value of forbidden energy gap for an insulator will be of 10eV.

·        For some insulators, as the temperature increases, they might show some conduction.

·        The resistivity of an insulator will be in the order of 107 ohm-meter.